JPS584868B2 - Film scanning synchronizer for television image transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film scanning synchronizer for television image transmission.

When projecting a film image onto a television, unlike screen projection, the problem is that the film feed speed (
The difference is that the number of frames per second) and the number of images per second on television.

In other words, while 16mm and 35mm standard film have a frame rate of 24 frames per second, the standard television format (NT
SC method), the number of images per second is 30 (60 fields, 3
0 frames), so if a standard screen projector is used in conjunction with a television camera to transmit film, clear horizontal stripes moving up and down may appear in the image due to the relationship between the projector's shutter and the television's scanning. ,
In addition, intense flickering occurs, making it impractical.

In order to solve these inconveniences, television projectors use a drive system different from that of ordinary screen projectors.

Typical conventional television projectors can be roughly divided into intermittent type projectors and continuous type projectors, depending on their driving method. This method projects images onto a television camera; the latter uses a mechanism such as a rotating mirror wheel or a rotating prism to continuously feed the film and use a mechanism such as a rotating mirror wheel or a rotating prism to switch by lap dissolve, projecting a continuous image without blinking. This is a method to do so.

However, in the former case of conventional television projectors, the intermittent feed mechanism is complicated and mechanical failures are common, while in the latter case, the optical structure is complicated and maintenance is required. The problem is that it is difficult to adjust.

Furthermore, a flying spot scanner device is known as an imaging means whose main purpose is to transport a film image.

This device is an imaging device that focuses spot light on a cathode ray tube surface onto a film surface of a subject, and receives reflected or transmitted light with a phototube to perform photoelectric conversion.It is relatively easy to adjust and has excellent stability. Although highly advantageous, the control means for synchronizing the television signal and film advance rate leaves room for improvement.

The present invention proposes a novel method for synchronizing the film feed speed and the television signal when using such a flying spot scanner device.
The present invention will be described in detail below with reference to Examples.

FIG. 1 is a block diagram of the main parts of an embodiment of the apparatus of the present invention, and FIG. 2 is a waveform diagram of signals in each part of the apparatus shown in FIG.

Now, the apparatus shown in Fig. 1 shows the signal processing circuit system after the film position detection element (photoelectric converter) 1, and the optical system (a series of film scanning devices such as a flying spot tube, a projection lens, a film and a condenser lens). The film transport system is the same as a normal one, and the film transport system is one that continuously feeds the film, and these are not shown because they are no different from conventional equipment.

First, a photoelectric signal obtained by the film position detection element 1 is amplified by an amplifier 2 to obtain a predetermined photoelectric signal P, which is applied to a monostable multi-oscillator 3.

Here, it is converted into a drive bell signal P.S to be applied to the bistable multi-oscillator 4 and AND gate circuits 5 and 6, and these functions generate alternate reset pulses S1 and S2 for every other frame.

On the other hand, the constant setting circuit section R, C, R1, R2, R3 and the two integrators 7, 8 for obtaining a sawtooth wave signal corresponding to the film feed speed are driven by the reset pulses S1, S2. Then, two sawtooth waves A and B are generated.

However, these two sawtooth waves A and B are generated by two analog switches 9 and 10, a comparator 11, and
This is a reference wave for generating an output D which is alternately switched in accordance with the timing of the vertical planking signal F by a loop consisting of a gate circuit 12 and a bistable multi-oscillator 13.

Further, using the vertical planking signal F obtained from the television receiver, a sawtooth wave having the same frequency as this is generated by the integrator 14, and this sawtooth wave signal and the output D are applied to the adder 15. The combined output drives the vertical deflection coil of the flinder spot tube, and the film is scanned and synchronized.

Furthermore, at this time, a direct current is superimposed through the direct current power source 16 in order to align the raster with the center of the flying spot tube.

Note that in the timing chart of FIG. 2, the signal E. G,H
The waveforms ``and'' are the comparator 11, and, respectively.
These are signal waveforms at each end of the gate circuit 12 and the bistable multi-oscillator 13.

As is clear from the configuration of the above embodiments.

If the film feed speed is n frames per second, the two sawtooth wave signals A and B must each have a frequency of /2 frames and be out of phase with each other by 1 frame. No.

For example, if the film speed is 24 frames per second,
The frequency of each sawtooth signal A, B is 12 frames per second.

However, the above two sawtooth wave signals A and B are formed using, for example, the Kyuden converter 1 with reference to a film position detection signal detected by passing through a barcolation hole in the film.

I would like to add that I would like to explain an example of its operation.

In the embodiment shown in FIG. 1, the analog switches 9 and 10 are on when the output of the bistable multi-oscillator 13 is at positive potential, and off when the output is at zero potential, and the comparator 11 is connected to the output D and the comparison reference. When compared with the voltage D', each potential waveform E is positive when D D' and zero when D<D'.

The AND gate circuit 12 outputs a positive potential only when both the output E of the comparator 11 and the vertical blanking signal F are at positive potentials.

Furthermore, if one of the analog switches 9 and 10 is on, the other is off, and when the switch 9 is on, the sawtooth signal A that has passed through it becomes the output D as it is, and at the same time, It also enters comparator 11, and D'
It is compared with the DC voltage.

If this comparison voltage D' is set to 1/2 of the peak voltage of the sawtooth wave signals A and B, or a voltage larger than that, the voltage of the sawtooth wave signal A that has passed through the analog switch 9 becomes the comparison voltage. When D' is greater than D', the output of comparator 11 produces a positive voltage signal E.

On the other hand, if the output E of the comparator 11 becomes a positive voltage, the AND
An external vertical blanking signal F applied to the gate circuit 12 appears as an output G of the AND gate circuit 11.

Therefore, with this output G, the output of the bistable multi-oscillator 13 is inverted, and the output H at one end becomes zero potential and the output 1 at the other end becomes a positive potential (these two outputs are mutually complementary signals). As a result, the above analog switches 9 and 10
Invert each function.

At the same time, the output E of the comparator 11 also becomes zero potential.

Further, since the vertical planking signal F does not cause two or more consecutive outputs G from the AND gate circuit 12 and the analog switch 10 is turned on, the comparator 11 receives the other sawtooth signal. When the voltage B is applied, and the analog switch 9 is turned on, the output becomes a positive voltage when it exceeds the comparison voltage D', and the signal F appears at the output G of the AND gate circuit 12. The stable multi-oscillator 13 is inverted and thus restored to its initial state.

The waveform diagram (timing chart) in Figure 2 exemplifies the case where the film feed speed is 24 frames per second, and each frame of the film is divided into 2 (field) - 3 (field) - 2 (field) - 3 (field). As shown in the figure, each frame is scanned alternately in a 4-frame-5 frame format.

In other words, by comparing two sawtooth wave signals whose phases are 180° different from each other, with two frames as one cycle, with a reference voltage, a vertical planking signal is alternately superimposed on each sawtooth wave signal in two and three cycles. can be made,
Therefore, the film can be scanned every two or three fields.

Although this embodiment shows the case where the film feed rate is 24 frames per second, synchronization can be achieved in the same manner for other feed speeds.

In this apparatus, by selecting the time constant element, it is possible to freely adjust the synchronization between the television signal and the film feed speed within the range of 0 to 30 frames per second.

As described above, the film scanning synchronizer for television image transmission according to the present invention has first and second signals synchronized with each frame of the film having a phase difference of 180 degrees from each other.
Generate a sawtooth wave signal, select and output one of the sawtooth signals using a switch element, input the output sawtooth signal to a comparator, and compare the output from the comparator with vertical planking. The switch element is controlled by an AND signal with the signal, and the output sawtooth wave signal is superimposed on the vertical planking signal, thereby synchronizing the film feeding speed and the television signal. Therefore, the television image transmission from the projection film by the flying spot tube is performed in perfect synchronization. Moreover, according to this device, such synchronization adjustment can be performed automatically, so there is no need for operation or maintenance adjustment. Since it is not necessary, it is also extremely practical.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of signals at various parts of the apparatus. 1...Film position detection element, 2...
Amplifier, 3... Monostable multi-oscillator, 4...
...Bistable multi-oscillator, 5, 6...AND gate circuit, 7, 8...Integrator, 9, 10...
...Analog switch, 11...Comparator, 12...And gate circuit, 13...
...Bistable multi-oscillator.

Claims (1)

[Claims] 1. Generate two sawtooth wave signals having a phase difference of 180° from each other using the signal of the film position detection element as a reference, and guide the two sawtooth wave signals to two analog switches that operate in phase inversion with respect to each other. Select and output one of the sawtooth wave signals, guide a part of the output sawtooth wave signal to a comparator, and AND the output from the comparator and the vertical planking signal obtained from the television receiver. input to the gate circuit, drive the bistable multi-oscillator with the output of this AND gate circuit,
A television characterized in that it has a feedback circuit that controls opening and closing operations of the two analog switches using complementary outputs from the bistable multi-oscillator to synchronize the film feeding speed and the television signal. Film scanning synchronization device for image transmission.